Wireless signals are typically transmitted in the radio frequency (“RF”) range of the electromagnetic spectrum. Because there are so many RF signals travelling through the air at any given time, RF devices are equipped with electronics that can allow them to separate the desired signals from the RF noise and interfering signals. But distinguishing the desired signal from the noise and interfering signals can be difficult if the two signals are close or identical in frequency.
Ships and aircraft often include many different RF devices, including RADAR and radios, which serve different functions. Unfortunately, because these devices operate over the same or similar frequency ranges and because they are in close proximity to each other, they can be difficult, and sometimes impossible, to use simultaneously. When a transmit antenna is located near a receive antenna, the signal sent from the transmit antenna interferes with the signal the receive antenna is supposed to intercept, making the receive signal noisy.
Many schemes have been developed to reduce interference between nearby antennas, including using specialized electronic interference cancellers. Conventional electronic interference cancellers, however, are only able to cancel signals over a narrow frequency range with a narrow instantaneous bandwidth.